Such a video server is already known in the art, e.g. from the article "A store-and-forward architecture for video-on-demand service" by A. D. Gelman et al , Proc ICC '91, June 1991, pp. 842-846 and is referred to therein as an information warehouse.
The architecture proposed for the video server and shown in FIG. 3 of the article requires the use of a server control means, constituted by the IWH service processor, which is relatively complex because it has to perform both an over-all control, i.e. call handling, routing, billing, etc., as well as an individual control of the transmission of each video signal. The article thus fails to account for the fact that the latter control is very elaborate for the reasons considered in more detail hereafter.
Firstly, for the video server to be feasible, the storage of each video signal has to be distributed over a number of separately controlled memories. Indeed, on the one hand, do state of the art memories and digital video coding techniques do not allow video signals exceeding a certain length to be stored in a single such memory. On the other hand can it also be verified from the article "System architecture for a large scale video on demand service", by W. Sincoskie, Computer Networks and ISDN Systems 22, 1991, 155-162, that for "near video on demand" a better service, i.e. smaller waiting times, is only possible by spreading the storage of a video signal over a number of such memories.
Secondly, to provide the "interactive video on demand" service as defined in the first referenced article, the server control means in the known video server needs to handle not only a relatively large number of "interactive" control signals but has also to react to them by controlling each of the memory controllers accordingly. This control is particularly complex when, as stated above, the storage of the involved video signals is spread over various memories and the known server control means further needs to map the above control signals to the exact memory configuration in use in the video server.
Hence, from the above it may be concluded that, when in the known video server the server control means is kept relatively simple, the freedom with which the storage of the video signals may be spread over the memories is restricted which clearly leads to a loss of functionality.